The present technology relates to an optical disc apparatus for reading out information recorded on an optical disc medium, a control method of the optical disc apparatus, a control program of the optical disc apparatus and an information storage medium for storing the control program. Examples of the optical disc medium are a compact disc (CD), a digital versatile disc (DVD) and a Blue-ray Disc (registered trademark).
For example, optical disc media having a plurality of types such as a CD, a DVD, and a Blue-ray Disc (BD) are used as information storage media. For the optical disc media having a plurality of types, there is provided an optical disc apparatus capable of reading out information stored in the optical disc media. When an optical disc medium is newly set on such an optical disc apparatus, first of all, the optical disc apparatus determines the type of the optical disc medium set thereon and then reads out information from the medium by adoption of a read method according to the type (refer to a document such as Japanese Patent No. 4769150).
In general, the optical disc medium has a structure including a plurality of laminated layers such as a data recording layer used for recording information and a protection layer for protecting the data recording layer. In addition, there are differences in distance between the medium surface and the data recording layer (signal surface) among the types of the optical disc media. Thus, when the optical disc apparatus determines the type of the optical disc medium, while the optical disc apparatus is moving an optical pickup in a direction toward the optical disc medium, the optical disc apparatus radiates light to the optical disc medium and detects a medium-surface reflection signal reflected by the medium surface and a signal-surface reflection signal reflected by the signal surface. Then, the optical disc apparatus computes the distance from the medium surface to the signal surface on the basis of the position of the optical pickup when detecting the medium-surface reflection signal and the position of the optical pickup when detecting the signal-surface reflection signal. Finally, the optical disc apparatus is capable of determining the type of the optical disc medium from a result of the computation.